To easily and effectively obtain a new precursor intermediate of an important intermediate for the A ring of compactin and calcitriol, by reacting a benzylglycidyl ether with an anion of a prcpiolic acid alkyl ester.
A glycidyl ether of formula I (Bn is benzyl group or its analogue) is reacted with an anion of a propiolic acid alkyl ester (preferably propiolic acid ethyl ester) to obtain a compound of formula II (A is an alkyl). Specifically, the compound of formula I is preferably reacted, in the presence of a Lewis acid catalyst in a solvent, with the anion obtained from a propiolic acid alkyl ester and a base. The principal intermediate, represented by formula III, of compactin and calcitriol is obtained by the steps comprising hydrogenating reduction of the compound of formula II in the presence of a reduction catalyst, cyclization in the presence of an acid catalyst, epoxidation of the reaction product and then ring-opening of the epoxide.
TAKAHASHI MICHIYASU
OIZUMI MITSURU
